A volatile memory, which is incorporated in an electronic device such as an image forming apparatus, is normally supplied with power from a device power source (i.e., a power source of the electronic device), but from a backup battery when the power supply from the device power source is disconnected, whereby data can be kept retained in the volatile memory.
In, e.g., PTL 1, a memory board is proposed that changes the power supply source for a volatile memory from a device body as a drive power source to a backup battery and prohibits writing to the volatile memory when a detected voltage of power supplied from the drive power source becomes equal to or less than a predetermined value.